With performances from Peter Capaldi, imagine... marks the 500th anniversary of Machiavelli's notorious book The Prince. Famous for lines like 'It is better to be feared than loved', The Prince has been a manual for tyrants from Napoleon to Stalin. But how relevant is The Prince today, and who are the 21st century Machiavellians? Alan Yentob talks to contributors including Colonel Tim Collins, who kept a copy of The Prince with him in Iraq; plus Hilary Devey, Alastair Campbell and Game of Thrones writer George RR Martin.